Pull broach machine with work feeding table



' Feb. 26, 1946 B. WELTE 2,395,702

PULL BROACH MACHINE WITH WORK FEEDING TABLE Filed July 23, 1943 5 Sheets-Sheet l INVENTORH/Y/V A zerya ica n ezzer AT 7' OHNE Y5 B. WELTE PULL BROACH MACHINE WITH WORK FEEDING TABLE Filed July 23, 1943 5 Sheets-Sheet 2 1N VE N TOR 55176 7 82 Z M6222;

Feb. 26,3Q4fi B. WELTE I 395,702

PULL BROACHMACHINE WITH WORK FEEDING TABLE Filed July 23, 1943 5 SheecS-Sheet 3 I I, 13,. I v

BY I ATTORNEX-F.

Feb. 26, 1946. B. WELTE PULL B ROACH MACHINE WITH WORK FEEDING TABLE Filed July 23, 1943 5 Sheets-Sheet. 4

v /INVENTOR. zezz'ea'z Wazz'e,

Fb. 26, 1946. B. WELTE 2,395,702

PULL BROACH MACHINE WITH WORK FEEDING TABLE Filed July 23, 1943 5 Sheets-Sheet 5 Patented Feb. 26, 1946 PULL BROACH MACHINE WITH WORK FEEDING TABLE Benedict Welte, Lake Orion Township, Oakland County, Mich., assignor to Colonial Breach Company, Detroit, Mich, a corporation of Delaware Application July 23, 1943, Serial No. 495,856

8' Claims.

The present invention relates to a pull broaching machine adapted. to shuttle one or more breaches automatically through a breaching and breach return cycle. The particular embodiment illustrated is a pull down breaching machine adapted to operate four breaches simultaneously.

The time required to load the work in the work fixture of a pull breach machine is lost time since in an ordinary pull breaching machine the completed workpiece is removed and a new workpiece is inserted upon completion of the cycle when the machine is stopped. This lost time constitutes an appreciable portion of the breaching cycle, particularly where the machine is used to operate on a plurality of workpieces simultaneously. Accordingly, it is one object of the present invention to provide a machine of the type mentioned having a moving table for the work fixture which automatically moves out of breaching position upon completion of the breaching stroke, thus enabling the operator to reload the fixture during the breach return portion of the breaching cycle. This arrangement has the further advantage that it eliminates the hazard to which the operator is subject should the machine start while he is loading the work. This hazard is aggravated when the machine pulls a cluster of breaches because there is danger that the operators hands will be injured by one breach while he is locating the work for another breach.

Another object of the present invention is to provide a moving work supporting table for a pull down breaching machine having a novel means for discharging chips in such a manner that they will not find their way to the ways upon which the table slides or to any of the relatively moving parts of the table moving mechanism.

Another object of the present invention is to provide an improved means for moving the work table of the type mentioned.

Another object of the present invention is to provide an improved hydraulic circuit for automatically operating a hydraulic pull down breaching machine and a moving work table through an automatic breach shuttling cycle.

Another object of the present invention is to provide means for controlling the pressures in the hydraulic system to the end that the pressure source, which is a constant displacement pump, will operate against a reduced pressure during the movements of the work table and the breach handling cylinder.

Another object of the present invention is to provide improved means for preventing the breaching or breach handling cylinders from falling by gravity when the machine is stopped between broaching cycles.

Other objects of the invention will become apparent from the following specification, the drawings relating thereto, and from the claims hereinafter set forth.

In the drawings, in which like numerals are used to designate like parts in the several views throughout:

Figure 1 is a frontview of the machine;

Figure 2 is a section taken on the line 2-2 of Figure 1;

Figure 3 is a horizontal section taken on the line 3-3 of Figure 2;

Figure 4 is a vertical section taken on the line 6-4 ofFigure 3;

Figure 5 is a horizontal section taken on the line 5-5 of Figure 1;

Figure 6 is a section taken on the line 6.6 of Figure 3 with the casing and other parts of the machine broken away to show the valve operating mechanism;

Figure '7 is a section taken on the line 1-1 of Figure 6;

Figure 8 is a fragmentary sectional view of th trip dogs similar to Figure 3 but taken at a point near the top of the breaching ram; and

Figure 9 is. a diagrammatic view of the hydraulic circuit of the machine.

Referring to the drawings, the machine comprises a frame or casing It] made up of a pair of side walls I I, a front wall I2, and a rear wall l3. The side walls I I, as best shown in Figure 4, are provided on their inner sides at their forward portions with a pair of longitudinal rails I 4 upon which is supported a stationary work table sup,- port I5. A pair of transverse beams I6 extends between the side walls I I beneath the work table support IS in order to provide additional support and stiiiening for the same.

A pair of hardened steel ways I8 is secured to the support l5 and extends fore and aft in spaced parallel relation in order to provide a sliding support for a movable work table l9. The work table I 9 is provided at each side with an outwardly extending flange 20 over which lies a gib 2| which is secured to the support I5 by means of cap screws 22. The gibs serve to hold the movin table in contact with the ways I8 at all times.

As best shown in Figures 3 and 4, the moving table I9 is provided in the region between the ways l8 with four breach openings 24, the particular machine illustrated being adapted to shuttle four breaches simultaneously through the work. The stationary support I5 contains four similar openings 25 which are aligned with the openings 24 when the table I9 is in the broaching position illustrated in Figure 3.

The moving table I9 is also provided with a pair of openings 25 which is aligned with the two forwardly disposed openings 25 in the stationary support I5 when the moving table I 9 is in its outer or loading position. At that time the two rearward openings 25 in the: stationary support I5 are disposed rearwardly of the rear edge 21 of the moving table I9 and, consequently, the four broaches may be returned while the moving table is in its loading position. It will'be noted that the broach openings are located in two rows extending fore and aft of the table.

A pair of chip discharge openings 28 is provided between the moving table I9 and the stationary support I5, as best shown in Figure 4. Each of the chip discharge openings 28 intersects one of the two rows of broach openings 24 and 26. The chip openings are formed by the lower surface of the moving table I9 and the'upper surfaceof the support I5, and are located immediately inside the inner edges of the hardened ways I8. 'As a result of this arrangement, as the table [9 reciprocates back and forth chips which fall off the broaching tool as it passes through the openings 24 and 26 are discharged forwardly and rearwardly of the table through the openings 28. I

. The support I5 is provided with an opening 38, shown in dotted lines in Figure 3, which intersects the left-hand chip discharge opening 28 and is disposed forwardly of the front edge of the table I9 when the table is in broaching position. As a result of this arrangement, the chips which work forwardly through'the left-hand chip discharge opening 28 will not build up sufficiently to interfere with the movement of the table operating lever, hereinafter referred to, since they will fall through the opening 39.

Chips which work forwardly through the righthand chip discharge opening 28 are similarly disposed of by means of an opening 32, shown best in Figure 4. The opening 32, which, as hereinafter more fully described, contains the table moving arm, intersects the right-hand chip opening 28 rearwardly of the forward edge of the table I9 when the table is in broaching position and, consequently, discharges the chips before they can accumulate to such an extent that they will interfere with the movement of the table operating lever. I

It will be noted that in the region between the chip openings 28 the moving table I9 has'a downward projection which contacts the hardened way 34 secured to the support I5. Rearwardly of the way 34, as best shownin Figure 2, the support l5 has an upward projection which carries a hardened way 35 for supporting the rear edge of the table l9. At a point located forwardly of the broach openings 24, there is a gap between the forward end of the way 35 and the rearward portion of the downward projection of table I9 in which is located the extremity 35 of a lever 37 which is splined to the upper end of a vertical shaft 38 and which extends through the opening 32. As best shown in dotted lines -in Figure 3, the opening 32 is sector form in order to permit swinging movement of the arm about a vertical axis.

The extremity 35 of the lever 31 is provided with a slot 45, shown best in dotted lines in Fi ure 3, in which is received the extremity of a pin 42 journaled in the moving table 9, with the result that on swinging movements of the arm 31 the table will be reciprocated. The upper end of the pin 32 is sealed against chips by means of a plate 43. It will be noted that the extremity 36 of the arm 3? fits closely against the underside of the table I9 and the upper surface of the way 34, with the result that no chips can find their way into the slot 45. The extremeouter end of the lever 31 projects somewhat into the left-hand chip opening 28 and, accordingly, the forward portion of the chip opening 28 is enlarged by a recess =35 formed in the upper surface of the stationary support I5 to provide additional chip clearance.

The vertical shaft 38 is journaled at its upper end in a bearing block 48, which is fixed to the forward face of the forward beam I6, and is journaled at its lower end in a similar bearing block E9, which is secured to the underside of a shelf 50 which extends between the side walls II of the frame. A tube 5| surrounds the shaft 38 between the bearing block 48 and the :shelf 50 in order to prevent chips from getting shaft. Both of the levers 31 and 55 are splined to the shaft, with the result that they cannot rotate with reference'to the shaft.

The outer end'of lever 55 is provided with a pin 55 which extends through the arms of a yoke 51 carried in the forward end of a rod 58 which extends backwardly to the rear portion of the machine and, as hereinafter described, is connected to the hydraulic cylinder and piston unit which operates the moving table. It willbe observed that as a result of this driving connection the driving mechanism is protected. from chips and is located in such a manner that it will not interfere with the movements of the table or the breach.

As best shown in Figures 3 and t, means are provided for limiting the movements of the table in both directions. This means comprises a pair of hardened lugs 55 secured at each side in suitable recesses in the table I5. The pair of lugs at each side projects outwardly to a point flush with the outer edge of the table flange 2B and the flange 28 is removed in the region between the two lugs. Similar hardened lugs 62 are secured at each. side of the table in suitable recesses formed in the support I5, and the inner ends of the lugs 62 project into the spaces between the lugs 50 fomied by the removal of the flanges 20.

As a result of this arrangement, the outer ends of the forward pair of lugs 60 abut the inner ends of the lugs 62 when the table I9 is in the broaching position shown in Figure 3. When the table is retracted to loading position, the outer ends of the rearward pair of lugs 60 abut the inner ends of the lugs 52. Thus, there is provided a positive abutment stop for the table in both extreme positions of its movement. The abutments are located on opposite sides of the point of application of the table moving force The'machine'i's providedwith a pair of" heavy internal vertical columns 70* which project upwardlyabove-the-level of the table Hi. The outer edges of the columns I0, as best shown in section in Figure 3; are secured to the side walls II, while the inner edges of the columns 10' are securedtogether by a rearwardly bowed wall I2, which extends from the bottom of the machine almost to the top thereof. These columns support the broaching ram and the broach handling ram;

In Figure 3 is shown the manner in which the broaching ram is mounted for sliding movement on the columns I0. The ram i5 is of generally cylindrical construction with a pair of laterally projecting vertical ribs I3 having slots 'I'I formed therein. A, pair of hardened ways 18' is fixed to the: columns 10 in any suitable manner and pro jects into the slots I'I. Bronze wearing members 19 line the walls of the slots and'closely fit the inneredges of the ways 18' in order that the broaching slide or rain maybe accurately guided in its vertical movements. The wear members 1'9" are fixed to the ram and hence slide upon the surface of the ways I8; a

The ram I5 is hollow and contains a broach operating cylinder 82' which is centered within the ram by means of internal ribs 83 atthe top and bottom of the ram. As best shown in Figures 2 and 3, the broaching cylinder 82 is slidable with respect to a fixedpiston rod, indicated generally at 85. The rod is formed of two concentric tubular members, indicated at 86 and 81 'in Figure 3. The upper end of the rod is' connected to a stationary manifold 88 fixed to the columns I by means of a pair of laterally extending ears 89, shown best in Figure 5. The manifold is connected to a pair of pipes for ad-v mitting fluid to the cylinder. The arrangement of the manifold, cylinder and double piston rod is conventional and hence need not be illustrated or described in detail. It is sufficient to note that one of the two pipes connected to the manifold 88 communicateswith the space within the inner tubular member 81, while the other pipe connected to the manifold communicates with the space between the tubular members 86 and 81'. The interior of the inner tubular member 81 is in open communication with the interior of the cylinder 82 below the piston carried by the. double rod, while the space between the tubular members and 81 is in open communication with the cylinder at the opposite side of the piston.

The lower portion of the broachng ram has. a forward projection 90 upon the front face of which is mounted a bracket 92' which carries a pair of broach pullin chucks indicated generally at 94, one of which chucks appears in Figure 2. The other chuck, which is of' identical construction, is immediately behind the chuck 94, as viewed in Figure 2. Each chuck is a double chuck; that is, it contains means for gripping and pulling two broaches. Consequently, the machine is adapted to pull four brdaches simultaneously. The construction of the chucks is conventional and hence need not be described in detail. It is sufficient simply to note that when the broaching ram is at the top of its broach return stroke the release sleeve 95, which surrounds each pulling chuck, engages the un--.

derside of the support I5- or any other suitable abutment and is forced'd'ownwardl'y against the action of a plurality of spring pressed plungers 91.. In that position the chuck is in a broach: releasing condition and the broachesmay be inserted in orwi-thdrawn from" the; chuck: freely;

When the broaching stroke beg-inst. the ram portions: I 00. Thev channl-shaped framememeher I02 has a pair of. vertically extending: side;

portions I03 connected byfaalower crossmehrber' I04 and an upp'er' cross: member 4 I05". Apair of inwardlyprojecting vertically" extending hardened' ways I05 is fixedly secured" to; the, inner sides of the vertical sides I03 of; frame, I02, and these members project into suitable: slots I01'I formed inthe sides of a broach handling'slide I03. Wear plates I09'line the "slots: I01 and. engage the hardened ways I05; thewear' plates be ing fixed to the slide I08. and being: slidable. upon the ways I05.

A broach handling cylinder H0 is. secured within the interior of the: slide I0B- and centered: in position by means of a pair of'webs: I 'I I having circular openings which fit the cylinder. A bracket H5 is secured to the front face of the slide I08 in any suitable manner and carries a pair of double: chucks I'I6- similar in construction and mode of operation to the chucksSB' except that they are released at the endof the downward stroke of the; slide I=08- by reason of the engagement of. a. pair" of rods IiI'I fixed to the release sleeves of the" chucks with; a stop pad H8: carried by abracket I'I9- mounted on the lower cross frame member I04. The rods- II! are secured'to' the outer sidesof'thezchucks I I6 by threading them into suitable; openings in a pair of cars I20 formed on the side of. each. chuck.

The cylinder H0 mounted in the slide; I08 is supplied with fluid through a double piston rod,

indicated generally I22 in Fi ure 2; As: best shown in Figure 5, the piston rod I22 comprises: an outer tube I23 and an inner tube I24, bothof' which are fixed at their lower. ends to. amanifold- I25' carried by the cross member I04. The manifold is adapted to be. connected tora pair of pipes I26 and I2 1, one of which communicates with the space within the inner tubular member IZ' I and the other with the spacesbetween the tubular members I23 and. I24; As previously described in connection with the main breaching cylinder, the interior of the tubular member I24 communicates with the upper: end of the cylinder H0, while the space between the tubular members communicates with the lower end of the cylinder.

The arrangement of the trip dogs for controlling the hydraulic valves, which, in? turnv control the automatic" cycle of operation of the machine, is best shown in Figures 1, 3', 5, 6, '7 and 8;

Referring to Figure 6, the machine is' provided with four valve control rods which are actuated by the broachng ram and the-broach handlin slide: These rods include therod. I30, whiclris controlled, by the; broach, handling; slide; and the rods" I'3I.,. I32? and; I33, which are; controlled by the: broaching ram; The rod I32. is e Rod I30 is journaled at one end in a bearing boss I35 formed in the frame I93 and at the other end in a bearing I36 fixed in any suitable manner to the manifold 88, as shown best in Figure, 5. The forward end of the rod I30 carries a boss I31 provided with a pair of arms I38 and I39 disposed at an angle to each other and facing toward the adjacent edge of the breach handling slide I08.

As best shown in Figure 5, the broach handling slide I06 is provided with a T-slot I40 in which is secured a pair of trip dogs I42 and I43. The trip dog I42 is locatedadjacent the lower end of the broach handling slide in alignment with the arm I38, while the trip dog I43 is located adjacent the top of the breach handling slide and is adapted to engage the arm I39 when the slide reaches the lower end of its stroke. When the slide reaches the top of its stroke, the trip dog I42 engages the arm I38'and rotates the rod I30 clockwise, as viewed from the front of the machine. The rod is returned in a counterclockwise direction by engagement of the trip dog I43 with the arm I 39 when the slide reaches the lower end of its stroke.

The inner end of the rod I38 is fixed to a lever I44, the outer extremity of which is pivoted to a rod I45 which, in turn, is pivoted at its lower end to the extremity of a lever I46 fixed to the stem I41 of a control valve I48. The valve I48 is a dual valve, as more fully described hereinafter in connection with the hydraulic circuit.

The dual valve I48 is mounted on a valve panel I49; which is fixed to the rear side of columns bymeans of a pair of supporting members I50.

The rod I3I is journaled in a tube I52, which extends through an opening in the right-hand column 10 and is secured in position by means of a nut I53. The forward end of the rod I3! carries a boss I54 having an arm I55 which projects toward the main broaching slide and is adapted to engage a trip dog I56, which is secured in a T-slot I51 formed in the forward face of the breaching ram, as best shown in Figure 8. The position of the trip dog I56 is'such that when the breaching ram is at the top of its stroke, the dog engages the arm I55 and rotates the rod I3I in a clockwise direction. As soon as the broaching ram starts downwardly, the rod I3I is free to rotate'in a counterclockwise direction. The inner end of rod I3I carries a lever I58 provided at its extremity with an adjustable set screw I53 adapted to engage a roller I89 on the end of the stem of a valve I 6|, which is likewise carried on the panel I49. When the trip dog I56 engages the arm I55, the lever I58 forces the stem of valve I6I inwardly. The valve I6I contains a return spring which forces the stem outwardly and rotates the shaft I 3| in a counterclockwise direction when the broaching ram leaves its uppermost position.

Rod I32 is journaled in a sleeve I63 which extends through an opening inIthe column 10 and is secured by means of a nut I54. The outer end of the rod I32, as previously indicated, carries the starting handle I34, and the rod at a point intermediate its ends also carries a boss I65 provided with a downwardly projecting slotted member I66. The slotin the member I 66, as best shown in Figure 4, is adapted to receive the upper extremity of a lever I68 which is journaled on" a tubular member I69 which likewise projects through the column 10 and is secured by manually controlled in that it is rotated in one direction manually by the starting handle I 34;

means of a nut I10. The lever I68 carries intermediate its ends a lug or projection "I, which projects toward the breaching ram and is adapted to cooperate with a trip dog 12 secured to the broaching slide by means of the T-slot I51. As best shown in Figure 4, the projection HI and the trip dog I 12 are provided with interengaging cam surfaces so arranged that they will not engage until after the starting handle has been shifted to starting position by rotating it clockwise, as viewed from the front of the machine. The trip dog I12, as shown in dotted lines in Figure 4, is in the position it assumes when the bro-aching ram is at the bottom of its stroke. The trip dogs I56 and I82, shown in solid lines in Figure 4, are in the positions they assume when the breaching ram is at the top of its stroke. Upon shifting of the starting lever the lever I68, with its projection IN, is shifted toward the breaching ram and the projection I1I is then in position to be engaged by the trip dog I12. The trip dog I12 is located adjacent the top of the breaching ram in a position to engage the projection I1 I when the broaching ram reaches the end of its broaching stroke, at which time the trip dog will be efiective to rotate the lever I68 clockwise and thus return the rod I32 and starting handle I34 in a counterclockwise direction to the stop position.

The inner end of rod I32 is connected by a cross T coupling I15 to the stem I18 of a dual valve I 11.

The rod I33 is journaled within the tubular member I69 and carries at its outer end a boss I19 having a pair of arms I and I8I. The breaching ram is provided with a trip dog I82 adapted to engage the arm I80 when the broaching ram reaches the top of its stroke and thus rotate rod I33 in a clockwise direction. The ram is also provided with a trip dog I83 adapted to engage the arm I 8I when the broaching ram completes its downward or breaching stroke and thus return the rod I33 in acounterclockwise direction to its initial position. The boss I18 is provided with a pair of notches, one of which is adapted to receive a spring pressed plunger I84 in each of the rotative positions of the boss. The inner end of the rod I33 is connected by a cross T coupling I85 to the stem I86 of a control valve I88, more fully described hereinafter.

As best shown in Figure 6, the rod 58, which ary. A pair of pipes I91 and I98 is connected tothe opposite ends of the cylinder.

The upper end of the slide I9I is provided with a pair of trip dogs 200 and 20I. When the piston rod I is at its forward or left-hand position, as viewed in Figure 6, the trip dog 20I engages the lower end of a lever 262 which is pivoted'intermediate its ends on the bracket I93 by means of a pin 203. When the rod is at its rearward or right-hand position, as viewed in Figure 6, the trip dog 200 engages the lever 202 and rotates the lever in its opposite direction. The upper end of the lever 202 is slotted to embrace the spindle of a spool 205 fixed to the end of the stem 205 of a valve 207, The valve 201 is fixedly secured to the top of the bracket I93. As the re sult of this arrangement, the valve 231 is shifted at each extremity of the stroke of the work fixture or table.

As shown in Figure 3, the machine is provided with an additional control handle 208, similar to the handle I 34 but positioned at the left-hand side of the front face of the machine. The handle 208 operates a lock which normally prevents operation of the handle I34. It thus constitutes a well-known form of safety device since the starting handle cannot be shifted unless both hands of the operator are occupied. The machine also carries a handle 209 which operates a reversing and an emergency stop valve, hereinafter referred to.

The hydraulic circuit by which the machine is controlled is illustrated diagrammatically inFigure 9. In order to simplify the illustration, the concentric stationary piston rods 83 and 81 for the breaching cylinder 82 are illustrated as two separate pipes and the rods I30, I35, I32 and I33 for operating the control valves are shown as dotted lines extending in the plane of the paper from an end view of the rods. A number of the smaller fluid lines are also shown as single lines. The drawing is further simplified by omitting most of the lines which run from the various valves to the tank or low pressure reservoir. These lines are indicated by the letter T at their termination.

As shown in Figure 9, the hydraulic system includes a tank or low pressure liquid reservoir 22!] and a fixed displacement pump 22I having its inlet pipe 222 extending into the tank and its discharge pipe 223 extending to a speed and pressure control valve mechanism indicated generally at 224. The valve 22 has an internal cylindrical chamber 225 having a reduced end portion 226. The cylindrical chamber 225 contains a piston 221 which fits the cylinder and carries at one side. a valve plunger 228 which controls a port 229 leading, by means of pipe 230, to the tank. The opposite side of thepiston carries a plunger 23! which fits the reduced bore 225 and a spring 232 normally acts upon the piston 22'! to shift it in a direction to close port 229. The valve plunger 228 and the plunger 23! are of the same diameter, andthe entire piston and plunger assembly is provided with a longitudinal opening from one end to the other, as best shown in dotted lines inFigure 9.

The chamber 225 is in constant communication with the pump discharge line 223 and also with a passageway 233 which connects with an outlet pipe 234. The passageway 233 contains an adjustable throttle valve 235. The valve 235 is so constructed that it will not entirely close the passageway 223 but may be adjusted to provide a variable restriction to the flow of liquid in the passageway. The passageway 233 at a point beyond the throttle valve 235 is in constant communication with the right-hand end of the cylinder chamber 225 by means of a small bleed passageway 236 and a communicating passageway 23?. The passageway 231, in turn, communicates through a ball checkvalve 238 to the tank line 239.

The structure of the speed and pressure con- .trol valve so far described forms no part of the present invention, since it is conventional. The operation of the valve is as follows.

Fluid from the pump, which may flow unrestricted through the line 223 and chamber 225 spring 232 is .set.

to the passageway 233, is subject to a restriction at the throttlevalve 235 which causes a drop in pressure between that existing in the chamber Y225 and that existing at the discharge end of is constructed to permit opening of port 223 on a relativelysmall difference in pressure at the opposite sides of the piston, such as a difference in pressure in the order of eighteen pounds per square inch.

As a result of this arrangement, the piston 221 will shift to the right, thus opening port 223 at any time the pressure drop across the throttle valve 235 tends to exceed the pressure difference for which the spring 232 is set. This opening of port 229 by-passes a part of the constant flow of liquid from the pump to the tank and, consequently, reduces the flow across the throttlevalve 235 and thereby reduces the pressure-drop across the throttlevalve until the pressure drop falls to or below that for which the Accordingly, the structure so far described functions to maintain automatically a flow through passageway .233 of sufficient fluid to cause a given pressure drop determined by spring 232 across the throttle valve, regardless of the pressure existing in the passageway 233. Since the only way in which the pressure drop across the valve 235 can be maintained uniform is by maintaining the quantity of liquid which flows past .the valve uniform, the function of the valve mechanism so fardescribed is .to maintain a uniform rate of flow from passageway 233 to'pipe 234, regardless of the resistance against which the'pressure is flowing. The valve 235 is adjusted to pass the quantity of liquid necessary to operate the breaching ram at the desired cutting speed; consequently, the ram will move at that speed, even though the resistance to its movement is variable.

It will be noted that in addition to operating as a speed control valve the valve 223 also performs the important function of insuring that the pressure against which the pump is discharging during the breaching and broach return strokes of the ram never exceeds the pressure required to move the breaching ram at the desired speed plus the small constant pressure drop across the throttle valve 235. This follows from the fact that the pressure in the pump discharge line 223 is always equal to the pressure line 233 plus the drop in pressure across the throttle valve .235, and the pressure in chamber 225 is automatically maintained at a sufiicient level to pass the desired quantity of liquid through the valve 235 regardless of the resistance to ram movement. This is an important feature inasmuch as during a considerable portion of the cycle little resistance is offered to the movement of the broaching cylinder, and it is undesirable to have the pump operating at a high pressure during those periods since it would waste power and, moreover, that power would show up in the form of heat in the liquid.

The check valve 238 is a safety release device,

and the spring which normally holds the check valve closed is set to open at the maximum allowable pressure, which may be in the order of a thousand pounds per square inch. If at any time the resistance is sufficiently great to build up a pressure in pipe 234 and passageway 233 sufficient to open the check valve 238, the fluid in passageway 231 will immediately flow to tank through line 239 and at a faster rate than it can be supplied through the small bleed passageway 236. As a result, the pressure in passageway 23-1 and, therefore, the pressure at the right-hand side of piston 221 will drop, allowing the pressure at the right-hand side of piston 221 to shift the piston to the right and open port 229, thus relieving the pressure on the system.

It will be understood that since the breach handling cylinder and the work table moving cylinder are much smaller than the breaching ram cylinder, they will require a smaller flow of liquid. Since valve 235 is set for the flow required to operate the ram cylinder, the valve 224 will not operate automatically as a speed or pressure control valve during the movements of the handling cylinder and table cylinder.

However, means are provided for limiting the pressure developed by the pump during movements of the broach handling cylinder and the table cylinder. This means includes a port 242 in valve 224, which connects passageway 231 and a pressure control line 243 and means hereinafter described for controlling the pressure in line 243.

The fluid from line 234 is conducted to a four- I valve, being provided with a pair of pilot lines 264 and 265 leading to opposite ends of the valve. On admission of pressure to pilot line 264 and connection of line 265 to the tank, the valve spool is shifted to the right into the position shown in the drawings, while it is shifted;

in the reverse direction if pilot pressure is applied to line 265 and line 264 is connected to the tank.

Pilot lines 264 and 265 are connected to ports 266 and 261 of a rotary four-way valve 268. Therotary valve 268 comprises one portion of a dual reversing valve, the other portion being indi- V cated at 269. The two valves are connected by a shaft 216, indicated in dotted lines, to the reverse control handle 269, which may be mounted in any convenient location on the machine. The reversing valves 268 and 269 are illustrated in their forward or normal position, at which time port 266 communicates with. port 21I and'port 261 communicates with port 212. Port 21I is connected to port 213 of the four-way valve 261 by means of a line 214, and port 212 of valve 268is connected to a port 215 of valve 261 by means of a line 216.

As previously indicated, the valve 261 is a fourway valve controlled by trip dogs 266 and 26l connected to the piston of a movable work fixture, piston and cylinder unit I96. The spool and ports of valve 261 are generally similar to those of valve 256 except that the spool 218 is provided with an enlarged end portion 219 having a pair of spaced notches 286 and 28! adapted to co-operate with a spring-pressed detent 282, which acts to hold the spool against accidental displacement from either of its two positions of adjustment. When the spool is in the position shown in the drawings which it occupies when the piston is at the lower end of cylinder and piston unit I96 and the work fixture is in its loading position, pressure is transmitted from line 284, which is connected to the pump discharge pipe 223 through line 285 to port 286, which is in communication with port 215. At the same time the tank line 281, which is connected to port 268, is in communication with port 213 and line 214. Pilot pressure is thus transmitted through valve 261 to line 216 and thence through valve 268 from port 212 to port 261 to pilot line 264 to the left-hand end of the main four-way control valve 256. At the same time, the right-hand pilot line 265 of valve 256 is connected to the tank through ports 266 and 211 of valve 268, line 214, port 213 and port 288 of valve 261, and line 281. This serves to hold the spool 252 f valve 256 in the right-hand position shown in Figure 9.

When the work table is shifted to its broaching position, the spool 218 of valve 261 is shifted to its upper position, thus reversing the connections to lines 214 and 216. At that time the pilot pressure flows from port 286 to port 213, through line 214, from port 21I to port 266 of valve 268, and thence to the pilot line 265 at the right-hand end of valve 256. At the same time, the pilot line 264 at the left-hand end is connected with the tank through valve 268, line 216, and by communicating ports 215 and 211, passageway 289, and port 288 of valve 261.

As a result of this arrangemenait is apparent that the main four-way valve 256 is reversed at each end f the stroke of the work fixture cylinder and piston unit I96. If at any time during the cycle of operation it is desired to reverse the machine, the dual valve 268 and 269 is shifted to its reverse position. This reverses the connections between lines 264 and 265, on one hand, and lines 214 and 216, on the other, and thus reverses the position of spool 252 of valve 256 with respect to the position of spool 218 of valve 261. In the reverse position of the valve 268 port 212 is in fluid communication with port 266 through the space 262 in the valve stem formed in the rotatable plug 293 of valve 268, and port 261 is in communication with port 21I through the opening 294 in the valve plug. In the position shown in Figure 9, the communication between ports 261 and 212 is through the opening 295 in the valve plug, shown in dotted lines. When the reversing handle 269 is shifted to the stop position, indicated by S in Figure 9, the lands 296 and 291 block ports 266 and 261, with the result that no fluid can flow through the valve 266.

The valve 259, which ,forms part of the dual reversing valve, is identical in construction to valve 268 except that the lands 366 and SM on the valve plug have cut-away corners at 362 and 363, with the result that when thevalve is in its central or stop position fluid may flow from port 364 and port 365 through the passageway 366 in the valve plug to port 361. When valve 269 is in the forward position, shown in the drawings, port 365 is blocked because of the fact that port 368 is plugged, while port 364 is connected to port 361 through passageway 366. When the valve is shifted to reverse position, ports 365 and 361 are connected through passageway 306 and port 383 is blocked.

All of the parts in Figure 9 are in the position they assume when the machine is automatically stopped at the end of a broaching cycle and is in condition to be started on a new cycle of operation of the starting handle I32.

In the stop position illustrated, the valves are in such a position that fluid from pipe 234 may flow through valve 258 from port 254 to port 255 and thence to pipe 255. Pipe 256 is connected to a check valve 3H1, which is so arranged as to permit relatively free flow from pipe 256 to a pipe 251, but no return flow. Pipe 256 is also connected to a valve 3I I. Valve 3| I is provided with a pair of ports 3I2 and 3l3. Port M2 is connected to pipe 255, while port 3I3 is connected to pipe 3M which, in turn, is joined by previously mentioned pipe 251. The spool 3I5 of valve 3 is normally urged by spring 3I6 into the position shown in the drawings, in which the land 3 I! of the spool blocks communication between ports (H2 and 3l3. However, when pilot pressure is applied to the pilot line 3I8, which is connected to the lower end of the valve, the spool will be lifted, permitting communication between the ports 3I2 and 3l3. During the upward move ment of the valve spool the fluid trapped above the land 3!! is discharged through a small passageway 3I9 to the port 312. From pipe 3! the fluid may flow through a short branch line 328 to a pilot operated valve 32 I, which, in turn, is connected to a pipe 322. Valve 32I operates to block the how of fluid from pipe 323 to pipe 322 except when pilot pressure is applied to the pilot line 323 leading to the upper end of the valve.

Valve 32l may be of any desired construction; for example, it may be identical in construction to valve 250 except that the ports corresponding to ports 255 and 268 are blockedand the pipes 328 and 322 are connected to the ports which correspond to'the ports 254 and 251 of valve 25!].

Pipe 322 connects to a foot valve 324, which functions to permit relatively free flow from line 322 to line 325 but ofiers suiiicient resistance to return flow from line 325 to 322 to. prevent the fluid trapped in the upper end ofthe cylinder I I8 from discharging through the piston rod I23 and pipe 325 under the influence of gravity acting on the cylinder and broach handling slide. The interior of valve 324 contains a cylindrical housing 325 provided with a pair of ports 321 and 323 and a spool 329 provided with a. land 338 which, when the spool is held in its lower position illustrated by spring 33!, blocks communication between ports 321 and 328. Port 327 is connected by means of a passageway 332 to the space at the lower end of the valve spool 329. Consequently, when the pressure in line 325, which is connected to port 32?,reaches an amount suflicient to overcome the influence of spring 33I, spool 329 will lift, allowing flow from port 32'! to port 328 and thence through passageway.333 to line 322. The tension of spring 33I is adjusted so that it will not open until the pressure in pipe 325 exceeds the pressure which is induced by the force of gravity acting upon the broach handling slide. Port 32! is also connected by passageway 334 to a channel 335 of a spring-pressed check valve 338 which normally blocks a port 331 connected to "passageway 333. The check valve 336 will permit relatively free how from line 322 through passageways 333 and 33! to channel 335 and through passageway 338 to port 32! and thence to pipe 325. When spool 329 is moved upwardly, the

fluid trapped at the upper end is'discharged to passageway 333 through passageway 338.

Pipe 3 M is also in communication with the upper end of the broaching cylinder 82 through a foot valve 323, which is identical in construction to foot valve 324, and through pipe 3, which is connected to the space between the two piston rods '83 and 81 represented by the pipe 86 in Figure 9.

Port 25? of valve 258 is in constant communication with the lower end of the broach handling cylinder H8 through pipe 258, branch pipe343, and pipe I23. Pipe 258 may also be connected through valve 344 and pipe 345 to the lower end of the breaching cylinder 82 throughplston rod 5'5. Valve 344 is identical in construction and mode of operation to valve 32I, .pre viously described, being controlled by pilot pressure in pilot lines 346 and 341.-

The fluid for operating-the work fixture cylinder and piston 136 is supplied through'line 254 to valve 358, which forms one of the valves of the dual valve unit I", the-othervalVe being indicated at 35L Valve 350 is identical in construction and mode of operation to valve 258, previously described, and hence need not be described in detail, while valve 35I is of the same construction except that two of the ports are plugged.

In the drawings, the'flow through valves 358 and 35! is indicated diagrammatically. Thus, in valve 355 the solid line 352 connecting ports 353 and 354 indicates that in the position of the valve illustrated in the drawings ports 353 and 354 are in fluid communication with each other. At the same time, assimilarly indicated, ports 355 and 355 are in communication. As -a result of this, line 284 is connected through valve 358 to line I91, which leads to the upper end-of the work fixture cylinder and 'piston'unit I86, while the line I98, which is connected to the lower end of the cylinder and piston unit I96, is connected through ports 355 and 356 of valve 350 to tank line 359. When valve 358 is shifted by clockwise rotation of the starting handle I34 piston and cylinder unit I93 and connecting the upper end to the tank. This immediately starts movement of the work fixture from its loading to its broaching position. The pilot line N8 of valve 3! I is connected to line I38 and hence pilot pressure is applied to valve 3 when the starting valve is shifted to starting position.

When the machine is in the stop position illustrated, valve 35l connects a line 38I with a line 362, whichfin turn, is connected to port 301 of valve 263 and thence through passageway 385 to port 304, from which it is connected by a short line 353 to the pressure control'line 243. Consequently, when the valve 35I is shifted to its starting position, flow of fluid under pressure in line 332 is blocked, as indicated by the dotted lines on valve 35! in Figure 9. The dual valve IT! is returned to starting position, as previously indicated, at the end of thedownward stroke of the breaching cylinder 82 by reason of the engagement of the trip dog I12 with the projection ill on lever I38.

The pilot pressure for controlling valve 32I is controlled by valve I88, .which is also identical in construction to the valve 268, previously described. When the parts are in the stop p0- in the drawings.

nected bya branch line 364 through valve I88 I to the pilot line 323 leading to the upper end of valve32l, while the pilot line 366 to the lower end of valve 32I is connected through valve I88 to the tank line 361, and, consequently, valve 32! is open.

Valve I88 is carried by rod I33, which, in turn, is rotated by the arms I88 and I8I and trip dogs I82 and I83 as previously described. When the broaching ram reaches the bottom of its downward stroke, trip dog I82 engages arm ISI and rotates shaft I33 and thus valve I88 to a position in which the pressure line 284 is connected to pilot line 366, as indicated in dotted lines on valve I88, and the tank line 361 is connected to pilot line 323, thus shifting the spool of valve 32I and blocking communication between pipes 328 and 322. When the breaching cylinder 82 reaches its'uppermost position on its broach return stroke, trip dog I83 engages and rotates arm I88, thus returning valve I88 to the position shown in Figure 9.

The pilot lines 346 and 341, which control valve 344', are controlled by valve 388, which is one of the valves of the dual valve I48, previously mentioned, the other valve of the dual valve being indicated 369. Valve 368 is identical in construction to valve 268 and, in the position illustrated in the drawings, connects pilot line 346 throughline 318 to the pressure line 284 and at the same time connects pilot line 341 to the tank line 3". Under these circum stances, valve 344 is closed. When the broach handling cylinder II 8 reaches the end of its downward stroke, trip (10g I43 engages arm I39, thus rotating valve I48 counter-clockwise until pilot line 341 is connected to line 318 and thence to the pressure line 284, while pilot line 346 is connected to the tank line 31I, as indicated in dotted lines on valve 368. This shifts valve 344 and opens communication between pipes 258 and 345.

When the broach handling cylinder I I8 returns to its top position, trip dog I42 engages arm I38 and returns dual valve I48 to the position shown The other valve 369 of dual valve I48 is also identical in construction to valve 268 except that ports 312 and 313 are plugged. In the stop position illustrated, valve 369 connects the tank line 314 to a line 315 which leads to port 316 of valve I6I. When the dual valve I48 is shifted at the bottom of the downward stroke of the broach handling cylinder II8, communication between the tank line 314 and line'315 is blocked by valve 369.

Valve I6I, in the position shown in the drawings, provides a communication between port 316 and port 311, the latter being connected to the aforementioned line 36I. It also provides communication between the pressure control line 243 and a line 319, this connection being from port 388 to port 38I. Line 319 is connected'to tank line 362 through a pressure relief valve 383, which is identical in construction to the check valve 3I8 except that the spring which normally holds the check valve closed will not permit the valve to open until the pressure in line 319 exceeds a predetermined pressure necessary to operate both the broach handling cylinder III) and the work fixture cylinder and piston I96. The purpose of this valve is to prevent the pressure in pressure control line 243, and, consequently, the pressure discharged by the speed control valve 224 to line 234, from exceeding a predeter- ,sition illustrated, the pressure line 284 is conmined pressure during the movements of the broach handling cylinder H8 and the work table cylinder and piston unit I98 in view of the fact that these elements are not subject to the automatic speed and pressure control operation of valve 224. The pressure setting of valve 383, and, consequently, the pressure delivered to pipe 234 during the movements of the broach handling cylinder H8 and the work table is substantially less than the pressure required to operate the broaching cylinder 82.

When the machine is stopped, it will be noted that the pressure control line 243 is connected through line 363, ports 384 and 381 of valve 269, line 362, valve 35I line 36I through ports 311 and 316 of valve I6I, line 315, and valve 369 to the tank through tank line 314. Consequently, in the stop position there is no pressure in line 243 and, therefore, valve plunger 228 will be fully opened and the pump will discharge through line 238 to the tank at a very low pressure.

When the machine is shifted to starting position, valve 351 is shifted to disconnect line 362 from the tank. This enables the pressure to build up in line 243 and, consequently, during the operation of the work fixture the pressure supplied by the pump will be limited only by the setting of valve 383.

If at any time while the machine is stopped the broaching cylinder 82 sinks down by gravity, spring 385 in valve I6I will shift the spool of valve I6I to the right and thus block all flow through valve I6I. This not only disconnects the line 362 and, therefore, line 36I from line 315, which is connected to tank when the machine is stopped, but it also disconnects line 243 from the pressure relief valve 383, thus enabling the pressure to build up in line 243, As soon as the pressure builds up in line 243, the valve 224 will close and raise the pressure supplied .to the upper end of the broach cylinder 82, thereby returning it to its upper position. This insures that the broaching cylinder will not sink downwardly by gravity while the machine is in its stop position and the pump is operating. It also insures that the cylinder will be returned to starting position as soon as the pump is started after an idle period.

The machine operates in the following manner. With the parts in the stop position shown in the drawings and the pump running, passageway 231 in the speed and pressure control valve 224 will be connected directly to tank by lines 243, 363, valve 269, line 362, valve 35I, line 36I, valve I6I, line 315, valve 369, and tank line 314. Consequently, the pressure in chamber 225 at the left-hand side of the piston 221 will not exceed the low pressure required to collapse spring 232, and all of the oil discharged by the pump will flow through port 229 to the tank through line 238 except the very small amount which will flow through the bleed passageway 236.

It will be noted that if while the machine is in the stop position illustrated the broaching cylinder 82 sinks down by gravity, trip dog I56 will leave arm I55 and allow the spring 385 of.

This arrangeturned to the top, of its stroke. ment, therefore, constitutes an automatic means for prefllling the broaching cylinder so that it will be at the, top of its stroke when the machine starts. At the same time, this arrangement will automatically insure that the breach handling cylinder remains at the top of its stroke. Incidentally, it may be noted that the foot valves 324 and 340. normally serve to prevent either of the cylinders III) and 82 from falling by gravity when the machine is in its stop position. Consequently, the prefill arrangement need only take care. of sinking movements due to unavoidable leakage.

It being assumed that the workpieces are secured to the moving work table I9 by any suit' able work holding fixture, not shown, the machine is started by rotating, lever I34 'in a clockwise direction. This rotates the dual valve I'll from the position in which the flow conditions are illustrated in solid lines in Figure 9 to the position in which the flow conditions are illustrated in dotted lines. One of the valves of the dual valve I'I'I, namely valve 35I, is thus shifted to a position to block flow through the previously mentioned path from line 243 to'the tank. This follows from the fact that line 362 is then no longer connected to line 361. When this occurs. the pressiu'e in line 243 then becomes subject to the control of the pressure relief valve 383, being connected by means of valve I! toline 319 and thence through the pressure relief valve 333 to the tank line 382. The setting of the pressure relief valve 383 is such that the discharge to the tank will occur at a pressure in excess of that required to operate the work handling cylinder and piston I 96 and suflicient to operate the broach handling cylinder III).

Fluid will then flow from line 284 through the other valve 350 of the dual valve I IT in the dotted line path to line I38, which is connected to the lower end of the work handling piston and cylinder unit I96, thus causing the piston to move upwardly, as viewed in Figure 9, and shift the work table into broaching position. During this movement the liquid in the upper end of the cylinder and .piston unit I96 returns to tank through line I91, valve 350 and line 359.

When the broaching fixture reaches broaching position, trip dog 200 on slide I9I shifts the spool 218 of valve 201, thus reversing the pilot connections to valve 250, in the manner previously described. When the spool of valve 253 thus shifts to the left, fluid under pressure in line 234 is transmitted to pipe 258 and flows unrestricted through line 343 and outer piston rod I23 to the lower end of the broach handling cylinder ,9, causing it to move downwardly. At the same time, the fluid in the upper end of the cylinder returns to tank through the inner piston rod I24, pipe 325, foot valve 324, which then opens to permit flow from port 321 to port or channel 328, and thence. through valve 32I, pipes 320 and 3M, valve 3., pipe 256, and line 262.

At this time the pilot line 3I 8 of valve 3 is connected to line I98 which, in turn, is connected to pressure through valve 350 and line 284, and, consequently, valve 3II is open to permit the above described return flow.

During the downward movement of the work handling cylinder I I0, valve 344 blocks flow from line 258 to line 345 by reason of the fact that pilot pressure is connected to the left-hand pilot, line 346 by means of valve 368.

During the broach delivering or downward stroke of the broach handling cylinder IIII, line 243 limits the pressure delivered by valve 225 by reason of the connection of line 243 to tank through valve IiiI and the pressure relief valve 383. During this movement of the broach handling cylinder, therefore, valve 224 does not act as a speed control valve but simply as a pressure relief valve, due to the fact that the flow required to operate the broach handling cylinder is not suflicient on passing throttle valve 235 to cause a pressure drop sufficient to overcome the effect of spring 232. However, the pressure in valve chamber 225 cannot exceed the pressure determined by the setting of relief valve 383 plus the pressure required to overcome the spring 232 and, consequently, valve plunger 228 opens to a degree suflicient to maintain the desired pressure in the chamber 225 and line 234.

When the broach handling cylinder I I0 reaches the lower end of its stroke, trip dog I 43 engages arm I 39 and shifts the dual valve I28. One portion of the dual valve, namely valve 339, is thus shifted into a position in which communication from line 315 to the tank line 314 is blocked. This insures that the pressure control line 253 and the'branch thereof which includes line 363, valve 233, line 362, valve 35I, line 35I, valve IiiI- and line 315 will not be connected to tank when the valve 35I is subsequently returned to the position shown in the drawings. The other valve 368 of the dual valve I48 on such shift reverses the. pilot connections to valve344 and thus permits the fluid under pressure in pipe 258 to flow to pipe 365 and thence to the lower end of the 1 broaching cylinder 82 in order to start the downward or broaching stroke. of that cylinder. As soon as the broaching cylinder leaves its upper position, valve I6! is shifted into blocking position, disconnecting line 243 from the pressure relief valve 383 and tank line 332. This immediately eliminates control of valve 224 by the pressure relief valve 383 and enables the valve 224 to act as an automatic speed control and pressure relief valve during the remainder of the broaching or downward stroke of cylinder 82. During the broaching stroke, the return flow from the upper end of the cylinder 82 occurs through, the outer piston rod 86, pipe 3M, foot valve 340, pipe 3M and the open valve 3 to pipe 256 and thence through valve 250 to the tank line 262.

When the broaching cylinder-reaches the end of its broaching stroke, the trip dog I82 engages arm I 8| and thus shifts valve I88 to the position in which the flow is indicated in dotted lines in Figure 9. In this position pilot pressure is applied to the lower pilot line 353 of valve 32I and the valve spool assumes the, position in which it blocks flow between, pipes 320 and 322. At the same time, trip dog I12 engages the cam projection I'II' on lever I38, thus returning the starting handle I34 in, a counterclockwise direction to its stop position and, therefore, returning the dual valve ill to the position shown in Figure 9. The return of valve 35%, forming part of the dual valve I'II, to the position shown in the drawings returns the valve to the solid line flow conditions illustrated in which the pilot line BIB from the valve 3 is connected to the tank line 359 and, consequently, the valve 3| I blocks the return of fluid from the upper end of the cylinder 82 and positively stops the broaching stroke at the point determined by the setting of the trip dog I82. This makes it possible to adjust the broaching stroke to suit the needs of any particular job. It will be understood, of course, that any adjustment of the positionof trip dog I82 will be, accompanied by corresponding adjustment of trip dog I12 since both must operate at the same time.

When the valve 353, which forms part of the dual valve Ill, is thus returned to the position shown in the drawings, the fluid connections to the piston and cylinder unit I93 for the work fixture are reversed and fluid under pressure from line 284 flows through valve 350 to line I91 to the upper end of the cylinder, causing the piston to move downwardly as viewed in Figure 9 and retract the work from broaching position. During the return movement of the table the only pressure control eifective is the high pressure relief action of valve 224 made possible by ball check valve 238.

'When the piston of cylinder and piston unit I96 returns to the position shown in Figure 9, it shifts the spool 218 of valve 261 into the position shown in the drawings in which it connects pilot pressure through valve 268 to the left-hand pilot line 264 of valve 253, thus initiating the breach return stroke of the broaching cylinder 82 by reason of the fact that fluid under pressure in line 234 then flows through valve 259 to line 256 through check valve 3H3, line, 251, line 3I4, foot valve 340, pipe 34f and the outer piston rod 86 to-the upper end of the broaching cylinder 82. The fluid in the lower end of the cylinder 82 returns to the tank through the inner piston rod 8'I, pipe 345, valve 344, pipe 258 and valve 250 to the tank line 262.

When the 'broaching cylinder reaches its uppermost position shown in the drawings, trip dog I83 engages and shifts arm I80 to the position shown, thus rotating valve I88 .until it assumes the position in which the flow is indicated by solid lines in Figure 9. In that position, pilot pressure is applied to the upper end of valve 321 by pilot line 323, thus causing the valve 32! to open and permit flow from pipe 320 to pipe 322 and thus through the foot valve 324 past the check valve 336 therein to line 325 and thence to the inner piston rod I24 of the work handling cylinder H0. This starts the broach return stroke of the work handling cylinder IIU.

At the same time valve I88 is shifted, trip dog I55 returns arm I55 to the position shown in Figure 9, thus rotating shaft I3I in a clockwise direction and returning the spool'of valve I6l to the position shown in which it permits free flow from port 316' to port 311 andfrom port 330 to port 38L As a result of the shift of valve IBI, the pressure in line 243 during the broach return movement of the broach handling cylinder II is controlled by a pressure relief valve 333, in the manner previously described.

. When the broach handling cylinder IIS reaches the upper end of its broach return stroke, trip dog I42 engages and shifts arm I38 and thus dual valve I48 to the position shown in the drawings in which line 315 is connected to tank through valve 339. This brings the machine to a stop because the next operation in the cycle must he the work advancing stroke of the table and that can only be initiated by manual shift of the starting handle I34. When the machine thus stops, line 315 is connected through valve I BI, line 36L valve 35L line 362, valve 269, line 363 to the pressure control line 243, thus causing the valve 224 to discharge to tank at negligible pressure. The shift of valve 358, which forms part of the dual valve I48, restores the pilot lines to valve 344 to the condition in which that valve blocks fluid flow from line 258 to line 345 and thus completes the return of all parts to the stop position illustrated.

The stop and reverse valve is a dual valve comprising two valves 263 and 269. The valve 268 serves, when the reversing handle 289 is shifted from the forward position indicated F to the reverse position indicated R in the drawings, to simply reverse the pilot connections to the main control valve 259 and, consequently, reverse the direction of operation of the broaching and broach handling cylinders with respect to the direction they normally operate for a given position of the work table. The valve 269 performs nofunction when'tlie dual valve 268-459 is shifted to reverse position, but it is employed to stop the machine when the handle 209 is shifted to the intermediate stop position indicated S. In that position the'pressure control line 243 is connected through line 363 to the tank port 335 and, consequently, the valve 224 discharges to tank at low pressure. In the intermediate stop position, all ports of valve 268 .are

blocked and no function is performed by that valve.

Although only one form of the invention is shown and described herein, it will be appreciated that various modifications and alterations may be made in the machine without departing fromthe spirit of the invention or the scope of the appended claims.

What is claimed is: V

1. In a pull down broaching machine, a vertically operable broach handling cylinder and piston unit, a vertically operable broach pulling cylinder and piston unit, a source of liquid under pressure and hydraulio.control means for automatically operating said cylinder and piston units in succession through a breaching cycle and bringing them to a stop in their upper starting positions, said control means including valves and conduits for maintaining one end of each cylinder in fluid communication with said source when the cylinder and piston unitsiare, in their starting positions, said one end of each cylinder being the end the admission ofiiquid to which effects upward movement. thereof, a by-pass valve for discharging the fluid from said source at low pressure, means to open said by-pass valve when both of said cylinder and piston units are in their starting position and the machine is stopped in order to reduce the pressuredeveloped at said source, said last named means including means to reduce the opening of said bypass valve and thereby increase the pressure communicated from said source to said cylinder and piston units in the event the movable element of one of said units sinks by gravity below its starting position prior to the start of the broaching cycle.

2. In a pull down broaching machine, a vertically operable broach handling cylinder and piston unit, a vertically operable breach pulling cylinder and piston unit, a source of liquid under pressure and hydraulic control means for automatioally operating said cylinder and piston units in succession through a breaching cycle and bringing them to a stop in their upper starting positions, said control means including valves and conduits for maintaining one end of each cylinder in fluid communication with said source being the end the admission of liquid to which effects upward movement thereof, and foot valves assume for exerting suilici'ent resistance to the return of fluid from said ends of said cylinders to counteract 'the'force of gravity, a by-pass valve for discharging the iiuid from said source at low pres sure, meansto open said 'by-pass'valve when both "of said cylinder and piston units are in their starting position and the machine is stopped order to reduce the pressure developed at said source, said last named means including means to reduce the opening of said 'by-pass valve and thereby increase the pressure communicated from said sourceto said cylinder and piston units inthe event the movable element of said broach pulling unit sinks by gravity below its starting position prior to the start of the breaching cycle.

3. In a'pulldown breaching machine, a vertically movable broach handling. cylinder and piston unit, a vertically movable broach pulling cylinder and piston unit, a constant displacement pump, hydraulic control means connecting the pump with said cylinders and motor and adapted to operate the same automatically through a breaching cycle including the successive Steps of a breach delivery stroke of said broach handling cylinder and piston unit, a breach pulling stroke of said broach pulling cylinder and piston unit, a breach return stroke of the breaching cylinder and piston unit and a broach return stroke of the breach handling cylinder and piston unit and then bring the machine to a stop, said control means including a by-pass valve for controlling the pressure developed by said pump and valves and conduits for maintaining a connection between the pump and the upper ends of both cyllnders when the machine is stopped, means for causing said by-pass valve to reduce the pressure developed by said pump to a minimum value when the machine is stopped, means for causing said by-pass valve to increase the pressure developed by the pump in the event the breaching cylinder sinks downwardly by gravity prior to the institution of the breaching cycle, and means for causing said by-pass valve to limit the pressure developed by the pump to an intermediate value during movements of the breach handling cylinder and piston unit.

4. In a Dull down breaching machine, a vertically movable broach handling cylinder and piston unit, a vertically movable broach pulling cylinder and piston unit, a work moving fluid motor, a constant displacement pump, hydraulic control means connecting the pump with said cylinders and motor and adapted to operate the same automatically through a breaching cycle including the successive steps of a work advancing stroke of said motor, a breach delivery stroke of said broach handling cylinder and piston unit, a breach pulling stroke of said broach pulling cylinder and piston unit, a work retracting stroke of said motor, a breach returnstroke of the breaching cylinder and piston unit and a breach return stroke of the breach handling cylinder and piston unit and then bring the machine to a stop, said control means including a by-pass valve for controlling the pressure developed by said pump and valves and conduits for maintaining a connection between the pump and the upper ends of both cylinders when the machine is stopped, means for causing said by-pass valve to reduce the pressure developed by said pump to a minimum value when the machine is stopped, means for causing said by-pass valve to increase the pressure developed by the pump in the event the breaching cylinder sinks downwardly by gravity prior to the institution of the breaching cycle,

and means ior causing said by-pass-valve to-iim it the pressure developed by the pump to aninter mediate value during movementscf the breach handling cylinder and-piston unitan'd the work moving fluid motor.

*5. In a pull down breaching machine, a vertical broach operating cylinder and pis'tom-a vertical breach handling cylinder and piston, a work fixture moving cylinder and piston, a source or liquid under pressure, a reservoir, a pair of fluid lines, a four-way VeJlVeadapted in one position to connect one of said lines to the source and the other to the reservoinand in other line being connected to the opposite ends of said breaching and breach handling cylinders, a valve for controlling operation of said work fixture moving cylinder and piston, a starting handle connected to said last mentioned valve and adapted when shifted in a direction to start the machine to shift said last mentioned valve in a direction to cause advance of the work fixture into breaching position, means actuated by completion of the movement of the work fixture into breaching position to shift said four-way valve to said other position, a valve normally blocking fiow from said other line to said breaching cylinder, means actuated upon completion of the breach advancing stroke of the breach handling cylinder and piston for opening said last valve, means actuated upon completion of the breaching stroke of the breaching cylinder and piston to return the starting handle to stop position and thereby reverse the valve for controlling operation of the work fixture piston and cylinder, means operated upon completion of the return movement of' the work fixture to return saidfour-way valve to said one position, and a valve operative to block flow of fluid from said one line to said broach handling cylinder and piston until the breaching cylinder and piston has completed its return stroke.

6. In a pull down broaching machine having an automatically operable means for shuttling a breach through a breaching and breach return cycle, a stationary work table support, a work table slidably mounted on the support, means to shift the table from a leading position to a breaching position, said table and support having openings for the passage of the breach which openings are aligned when the table is in broaching position, said table and said support being formed to define a chip discharge opening extending from one edge of the table and support to the other in the direction in which the table moves relative to the support and intersecting openings through which the breach passes.

7. In a pull down breaching machine having an automatically operable means for shuttling a plurality of breaches simultaneously through a breaching and breach return cycle a stationary work table support, a work table slidably mounted on the support, means to shift the table from a leading position to a breaching position, said table and support having openings for the passage of the breaches which openings are aligned when the table is in breaching position, said table and said support being formed to define archip discharge opening extending from a on automatically operable means for shuttlin a 10 plurality of breaches simultaneously through a breaching and breach return cycle, a stationary work table support, a work table slidably mounted on said support for movement from a leading position to a breaching position, said table having a plurality of rows of openings for the passage of the breaches through the table.

15 said table.

said rows extending in the direction of movement of the table, openings in the Work table support which are aligned with the table openings when the table is in breaching position, said table and said support being formed to define a chip discharge opening for each row of table openi ngs extending in the direction of movement of said table from one edge there of to the other, a table moving arm located beneath the table and pivoted for movement about a vertical axis, said arm having one extremity pivotally connected to the table at a point between adjacent chip discharge openings, and means for swinging said arm in order to shift BENEDICT WELTE': 

